As a travel marketer, there are myriad ways you can spend budgets to sell rooms, cruises, vacation packages, and everything in between. Unfortunately, you don’t always know who likes what, why they would be interested in your product, or even if they’re even in the market to buy.

Fortunately, there are data targeting tools to help identify key audiences for your brand. In addition to the still very important age and gender targeting methods of traditional video advertising, hotels, airlines and other brands can now use technology to reach even more defined and relevant audiences.

So, in the spirit of efficiency, here’s a travel marketer’s 101 on some of the most frequently used data sources, and how to apply them to your travel-marketing strategy.